The present invention relates to a cleaning apparatus of an electrophotographic copying machine.
In a conventional electrophotographic copying machine, for instance, a cleaning apparatus of a trailing type as shown in FIG. 1 is employed for cleaning residual toner off the photoconductor drum of the copying machine, which comprises an arm 2 which is swingable towards a photoconductor drum 1, a metallic thin plate 3 whose base portion is fixed to a top end portion of the arm 2, and a cleaning blade member 4 which is made of an elastic material such as rubber and is attached to the underside of the metallic thin plate 3. The blade member 4 is brought into pressure contact with the surface of the photoconductor drum 1 with a predetermined pressure by a spring member 5 which is connected to the arm 2 as shown in FIG. 1.
This cleaning apparatus has the shortcoming that as the photoconductor drum 1 is rotated in the direction of the arrow as shown in FIG. 1, the contact point of the blade member 4 with the surface of the photoconductor drum 1 is shifted from position P.sub.1 to position P.sub.2 , since the force is applied to the blade member 4 in the direction of the tangent at the position P.sub.1 and the metallic plate 3 is curved as shown by the broken lines. Thus, the angle .theta..sub.1 between the lower side of the blade member 4 and the tangent at the point P.sub.1 is decreased to .theta..sub.2. As a result, the cleaning performance of the cleaning apparatus is significantly decreased. In particular, in the course of the cleaning operation, when the blade member 4 comes into contact with a non-image area where there is substantially no toner on the photoconductor drum 1 and where the friction between the blade member 4 and the surface of the photoconductor drum 1 is much greater than in an image areas where toner is abundant, the blade member 4 is slightly shifted in the downstream direction in terms of the rotation of the photoconductor drum 1, away from a normal cleaning position, due to the greater friction and the force applied to the blade member 4 in the direction of the tangent at the contact point of the blade member 4 with the photoconductor drum 3. As mentioned above, in such a shifted state, the cleaning performance of the blade member 4 is decreased. Immediately after this, even if the thus shifted blade member 4 comes into contact with an image area where there is residual toner and the friction between the blade member 4 and the surface of the photoconductor drum 1 is less, the blade 4 remains shifted, with the decreased cleaning performance being maintained. Furthermore, depending upon the conditions of the surface of the photoconductor drum 1, including the presence or non-presence of toner thereon, the metallic thin plate and blade are caused to vibrate.